Permanent Chat Bans?

So, I had this idea. There are players who do not ever troll in-game, but are super toxic. I was wondering if you could like give them a permanent chat ban, like a permanent ban. Or make a warning in champ select that the player is toxic, so that the other players know to mute him. I just don't think a permanent ban for someone who doesn't troll in-game is worthy, since they will just make another account. Permanent bans should only be for people who use hacks or actually troll, like feeding or something like that.